Achieved by maintaining a relatively constant, effective drug level in the body with
concomitant minimization of undesirable side effects associated with a sawtooth kinetic pattern.

Define localized drug delivery.

Achieved by spatial placement of a controlled release system adjacent to or in the diseased
tissue or organ.

Define targeted drug delivery.

Achieved by using carriers or chemical derivatization to deliver drugs to a particular "target" cell type.

Briefly give five reasons that make liposomes suitable as drug carriers.

-Low toxicity profile
-Ability to incorporate both hydrophilic and hydrophobic drugs
-Protection of drug from inactivation in blood stream
-Variability in size to incorporate larger or smaller drug molecules
-Possibility of controlled delivery

One method to control the release of drug molecules is by use of chemically
controlled polymeric devices. In such devices the rate of active agent release from the
polymer is controlled by a chemical reaction that can be hydrolytic or enzymatic cleavage of
a labile bond, ionization or protonation. Describe what is the principal advantage of
chemically controlled systems over other types of controlled drug delivery systems?

Principal advantage is the biodegradation and elimination of the device.

Discuss ophthalmic solutions

-most common
-all ingredients are in solution
-uniformity is not a major source of concern
-there is little physical interference with the eye
-disadvantage is brief contact (or low residence time).

Discuss ophthalmic suspensions

-dispersions of insoluble drugs using suspending agents
-higher residence time than ophthalmic solution
-absorption takes place from soluble particles
-optimization of particle size important to facilitate dissolution/prevent
irritation
-optimum intrinsic solubility is needed for timely dissolution
-a critical advice to the patient is shaking the suspension.

Briefly describe how does precipitation occur in a protein/peptide formulation?

Association of the hydrophobic residues of the unfolded proteins results in aggregation.
Aggregation may be on a macroscopic scale, resulting in precipitation. Hydrophobic surfaces
accelerate aggregation and precipitation. Air is a hydrophobic surface, therefore aggregation
is also accelerated at the liquid-air interface.

What are three ways by which the precipitation of protein/peptide formulations can be prevented?

Addition of salts, surfactants, or polyalocohols may decrease aggregation and precipitation.

What are the other forms of physical instability that may occur in
protein/peptide formulations? Name at least two.

Denaturation and adsorption

What is the difference between chemical instability and physical instability of
proteins and peptides?

Chemical instability; results in the formation of new chemical entities by bond formation or
cleavage. Physical instability; involves changes in the secondary, tertiary, or quaternary
structure of the molecules.

What are the desired properties of antimicrobial agents used for ophthalmic products?

An ideal
antimicrobial agent for ophthalmic products should be broad spectrum, stable, compatible, and nonirritable
(will get full credit for any 3 of the above).

What is the relevance of controlled drug delivery to pharmacy practice?

Knowledge of various types of delivery devices, and the mechanisms of drug release, aids in proper consultation with the patients, as well as physicians, nurses and other healthcare professionals. Issues such as factors affecting drug release and absorption, in addition to other criteria, depend on the type of delivery device used. Pharmacists are in the best position to provide such
consultation, since the knowledge of drug delivery is primarily taught to pharmacists. In addition, as the most accessible health care professional, pharmacists are in the best position to convey the needs of the patients to pharmaceutical scientists conducting research in the area of drug delivery.

What are the two most likely mechanisms of the interaction of liposomes
with cells? Briefly describe in the specified space below.

For most vesicle compositions and most cell types, adsorption of the liposomes
to the cell surface and endocytosis are the dominant mechanisms of liposomecell
interactions.

What makes polymers different than small molecular weight compounds?
Briefly describe in the specified space below.

The magnitude of intermolecular interactions between polymers is much larger
than small molecular weight compounds. As a result a larger number of
interactions such as dipole-dipole, H-bonding, and ionic interactions take place
between polymeric molecules resulting in higher material strength.

Briefly describe one example of a contemporary method of parenteral drug delivery?

“Insulin pumps” is one example of a contemporary method of parenteral drug delivery. It is a battery operated
device about the size of a pager, which contains a reservoir filled with insulin, like a syringe. It utilizes a
computer chip that allows the user to control exactly how much insulin is delivered. Patient should wear it 24
hours per day. It delivers only one type of insulin, which generally is rapid acting insulin. Insulin is infused
through a set that is changed by the patient every 2-3 days. The delivery of insulin to the patient occurs in 2
ways: basal rate: a continuous infusion to cover between meals and at night at a rate that is programmed by the
wearer, and bolus doses: doses of insulin given with meals in an amount determined by the pump wearer
according to the amount of food eaten.

Briefly describe what are pyrogens and how are parenteral solutions tested for the presence or
absence of pyrogens.

Pyrogens are products of metabolism of microorganisms; endotoxins are the most prevalent lipopolysaccharaides
from gram negative bacteria cell wall.
There are two kinds of test for the presence or absence of pyrogens in parenteral solutions. Traditional test uses
rabbits, solution injected into the ear vein (n = 3) or washings from a sterile device, and measure body temperature
and limulus amebocyte lysate. The second test is amebocytes (circulating blood cells) of the horse shoe crab
(Limulus polyphemus), which contain a protein which clots in presence of bacterial endotoxins.